DESCRIPTION

The L4977A is a stepdown monolithic power switching regulator delivering 7A at a voltage variable from 5.1 to 40V.

Realized with BCD mixed technology, the device uses a DMOS output transistor to obtain very high efficiency and very fast switching times. Features of the L4977A include reset and power fail for microprocessors, feed forward line regulation, soft start, limiting current and thermal protection. The device is mounted in a 15-lead multiwatt plastic power package and requires few external components. Efficient operation at switching frequencies up to 500KHz allows reduction in the size and cost of external filter components.

■ 7A OUTPUT CURRENT

■ 5.1V TO 40V OUTPUT VOLTAGE RANGE

■ 0 TO 90 DUTY CYCLE RANGE

■ INTERNAL FEED-FORWARD LINE REGULATION

■ INTERNAL CURRENT LIMITING

■ PRECISE 5.1V ± 2 ON CHIP REFERENCE

■ RESET AND POWER FAIL FUNCTIONS

■ SOFT START

■ INPUT/OUTPUT SYNC PIN

■ UNDER VOLTAGE LOCK OUT WITH HYS TERETIC TURN-ON

■ PWM LATCH FOR SINGLE PULSE PER PERIOD

■ VERY HIGH EFFICIENCY

■ SWITCHING FREQUENCY UP TO 500KHz

■ THERMAL SHUTDOWN

■ CONTINUOUS MODE OPERATION